Can I simplify my battery charging?

[Refueler]

Battery manufacturers usually define 100% SOC as a particular voltage and tail current setting. If charged to this level the battery should deliver its published capacity.

Absorption voltage (for example, 14.6v ) with a tail current of 2%-0.5% is typical, but it depends on the particular type of battery. In practice, the tail current drops rapidly as the battery approaches 100% SOC so the difference between battery types is not as great as this large percentage spread would suggest.

If your battery manufacturer does not produce any guidelines, absorption voltage with a 1% tail current (4A for a 400Ahr battery) is a good starting point.

If the lead acid battery manufacturer you quote is indicating that more energy can be squeezed into the battery, but at the expense of damaging the battery, it makes no practical difference. We would want to stop charging before the damage occurs. We would also want our battery monitor to indicate 100% SOC at this point. The battery should meet its published capacity figures when the charge is terminated in accordance to the manufacturer’s guidelines (if the manufacturer is honest).

The one rule to keep in mind is that if you consistently terminate the charging too early before the recommended tail current value is reached, the lifespan of the battery will be reduced. The often conservative default settings on some charge sources will do this.

Note the above is for lead acid batteries only.

BTW the only reference I can find to Mallory batteries is as a manufacturer of small dry cell disposable batteries. Have they ever produced lead acid rechargeable batteries? If so I would be interested to see their published charging recommendations and if these differ from other manufacturers.

1. You basically have agreed with my statement as nowhere do you equate 100% as actual true 100% ... but state it as the state at which battery reaches its published capability.

2. Mallory became a division of a large International Company that produced many different energy products and solutions for world markets ... from the smallest toys to Space exploration and Aeronautics. As said Mallory became a division and the overall company was far more than just the Duracell you hint at. Mallory was bought and incorporated into successive organisations ... and then eventually split up and dissolved. Tech of course was passed on and we still see it today. The other divisions still today are influential in the stored energy market.

 

[Lomax]

I agree with those who've said there's no need for the switches, and all your chargers can be left permanently connected (via appropriately sized fuses, of course). There is one potential conflict that I don't think anyone's mentioned though: the periodic equalisation charge provided by some chargers for flooded batteries (not recommended for AGM/gel). This is a brief intentional overcharge of up to 16 volts (on a 12 volt system) which serves several purposes; it ensures all cells are equally charged (hence the name), it prevents stratification of the electrolyte, and it removes some of the sulfate build-up you get when float charging for long periods. When not overdone it both extends the life of your batteries and ensures they're operating at maximum capacity - but when multiple chargers have this capability it may happen too frequently, which will increase water consumption and may cause excessive wear to the plates. Both my charger/inverter (Mastervolt) and my PV charge regulator (Morningstar) can be configured as to the frequency and strength of equalisation charges - and I have disabled them completely on the Morningstar.

 

[geem]

I agree with those who've said there's no need for the switches, and all your chargers can be left permanently connected (via appropriately sized fuses, of course). There is one potential conflict that I don't think anyone's mentioned though: the periodic equalisation charge provided by some chargers for flooded batteries (not recommended for AGM/gel). This is a brief intentional overcharge of up to 16 volts (on a 12 volt system) which serves several purposes; it ensures all cells are equally charged (hence the name), it prevents stratification of the electrolyte, and it removes some of the sulfate build-up you get when float charging for long periods. When not overdone it both extends the life of your batteries and ensures they're operating at maximum capacity - but when multiple chargers have this capability it may happen too frequently, which will increase water consumption and may cause excessive wear to the plates. Both my charger/inverter (Mastervolt) and my PV charge regulator (Morningstar) can be configured as to the frequency and strength of equalisation charges - and I have disabled them completely on the Morningstar.

I don't know of a charger set for the correct chemistry that will do an automatic equalisation charge. The default is normally off.
Lots of manufacturers don't recommend it. For most lead acid batteries that get a full charge daily, there is no need to equalise.
Probably best to disable

 

[noelex]

It is a good point about the equalisation charge. This is another reason why highly user adjustable charge sources are better. You can disable the equalisation function on all but one charge source without needing to select unsuitable voltage set points.

Generally, I think equalisation is better performed manually where you can keep an eye on things. It is a good idea to turn off sensitive electronics when equalising. This also prevents non ignition protected devices switching on or off when there might be some hydrogen gas around. If you do allow your charge sources to automatically equalise, at least check all your electronics are OK with the high voltage.

Recommended equalisation voltages for flooded batteries are often around 16.2v (or higher in cold conditions) and this can be a little much for some 12v devices.

 

[Lomax]

For most lead acid batteries that get a full charge daily, there is no need to equalise.

Agreed, if batteries are regularly cycled equalisation is probably not needed and may do more harm than good - it's only beneficial after extended periods of float charging (like several months), especially for flooded batteries. May also be needed when new batteries have been added. The default for the Morningstar is every 28 days.